Systems for removing mercury from flue gas have been studied in various ways because the flue gas emitted from a boiler, which is a combustion equipment in a thermal power plant, contains high-toxicity mercury.
In general, the boiler includes a wet desulfurization equipment to remove sulfur from the flue gas. It is well known that, in a flue-gas treatment system that includes the desulfurization equipment as a flue-gas treatment equipment and the boiler, when the amount of chlorine (Cl) in the flue gas increases, a proportion of the amount of water-soluble divalent mercury to the amount of chlorine increases, making it easier to trap mercury in the desulfurization equipment. Based on the above knowledge, conventionally, a system for removing mercury, in which chlorine compounds such as CaCl2 is added to fuel to be fed into the boiler to improve mercury removal efficiency in the desulfurization equipment, has been proposed (Patent Document 1).
Patent document 1: Japanese Patent Application Laid-Open No. 2000-325747